Hello, I'm trying to remember the name of an old movie from my childhood. The story involves a boy who is sick with the flu (or some other similar illness) and who lives with his grandmother. He witnesses his female neighbor murder someone and the story involves him trying to prove it. He recruits his friends, one of whom is a girl who secretly likes him and another of whom is paranoid about catching his friend's illness, even going so far as to wear a mask when the two of them are speaking. Does anyone know the title of this film? I saw it on TV but I'm not sure if it's a TV movie or an actual movie.